Using a national survey of 88,183 adolescents in grades nine to 12, findings show marijuana use declined from 23.1% in 2011 to 15.8% in 2021, with first-time use before age 13 dropping from 8.1% to 4.9%. In 2021, use was highest among 12th graders (22.4%) and 11th graders (18.7%). Notably, in 2021, girls (17.8%) surpassed boys (13.6%) in reported use, reversing previous trends. While Asian, Hispanic, and white adolescents saw significant declines, Black adolescents reported a higher usage rate of 20.5% in 2021, revealing ongoing racial disparities in marijuana use.

Besides helping to collect samples or spot butterflies for research projects — non-professionals can now conduct actual laboratory work alongside professional researchers. Together with Danish high schools, the University of Copenhagen has shown that "extreme citizen science" doesn’t just strengthen student motivation for science, but also provides a unique contribution to the monitoring of Denmark’s marine environment.